Sound recording



April 18, 1944.

c. CHEDISTER SOUND R ECORDING Filed Oct. 11, 1940 5 Sheets-Sheet lINVENTOR J Mai-W April 18, 1944. c. CHEDISTER SOUND RECORDING Filed001:. 11, 1940 3 Sheets-Sheet 2 INVENTOR C.

2? AT RNEY April 18, 1944. c CHEDISTER 2,346,905

SOUND RECORDING Filed Oct. 11, 1940 3 Sheets-Sheet 5 AfiORNEY PatentedApr. 18, 1944 UNITED STATES PATENT oFFlcE SOUND RECORDING ConklingChedister, Livingston, N. J.

Application October 11. 1940, Serial No. 360,751

8 Claims.

The invention relates to sound recording and to a mechanism foroperating apparatus in predetermined automatic relation to reproductionfrom a sound record.

Objects and advantages of the invention will be set forth in parthereinafter and in part will be obvious herefrom, or may be learned bypractice with the invention, the same being realized and attained bymeans of the instrumentalities and combinations pointed out in theappended claims.

The invention consists in the novel parts, constructions, arrangements,combinations and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a parthereof, illustrate one embodiment of the invention, and together withthe description, serve to explain the principles of the invention.

Of the drawings:

Fig. 1 is a partly diagrammatic view of an apparatus embodying theinvention;

Fig. 2 is a wiring diagram of the apparatus shown in Fig. 1;

Fig. 3 is a diagrammatic view of typical portions of a sound recordembodying the invention;

Fig. 4 is a diagrammatic view of apparatus for recording the novel soundrecord of the invention; and

Fig. 5 is a view similar to Fig. 3 of a modified form of record.

The invention is directed to providing novel methods and mechanism forcontrolling the operation of apparatus in predetermined relation to thereproduction from a sound record. The invention also comprises a novelrecording method and means for producing a sound record capable offunctioning in and with said control mechanism and further comprises thenovel sound record so produced. The principles of the invention arebroadlyapplicable to sound records and sound recording of either thephotoelectric film type or the mechanical sound records, such as thedisc type. In the present application embodiments of only the latterform will be shown and described in detail, but the application of theinvention of the equivalent form of photoelectric records of sound onfilm will be obvious to those skilled in the art.

One object of the invention is to provide mechanism for effecting andcontrolling the actuation of film-feeding means in conjunction with theplaying or reproducing of sound from a sound record which contains soundsequences relating to the subject matter shown on the film.

The invention is especially applicable to the actuation of theframe-by-frame feeding mechanism of a still or slide film projector,primarily for the purpose of advancing the roll of film one frame at theend of a predetermined sound sequence on the record being played. Theprob lem of automatically operating film feeding mechanism inconjunction with the playing of a sound record is a dimcult one thefrequency of the operations is necessarily irregular because of thevarying lengths of sound sequences applicable to the various pictures inthe film. Many unsuccessful attempts have been made to produce apractical and inexpensive automatic mechanism for this purpose but priorto the present invention there has been no successful solution of. theproblem and the commercial method curi-ently employed is to provide anaudible signal (such as a gong sound) on the sound record at the end ofeach sound sequence so that an operator may manually actuate the filmfeed mechanism at each gong signal.

Another object of the invention is to provide a novel record havingrecordings thereon coordinated with and supplemental to the usualrecordings of sound sequences whereby an accurate and convenient controlof the film-feed actuating means is provided. The invention is designedto utilize for control spaces on the sound record which are silent, theterm silent being defined as a space in the record track having norecorded or impressed frequency and thus having a complete absence ofany frequency to which the phonograph pick-up would be sensitive. Onedifiiculty in attempting to utilize such silent spaces on a record forcontrol in the actuating circuit is that silent spaces frequently occurin the recordings of normal speech, music or other audio sequences.Consequently in previous efforts to utilize silent spaces for thispurpose it has been necessary to provide actuating mechanism which wouldfunction only upon a silent space of a predetermined and unusual lengthand to provide elaborate and unreliable devices for preventing controlactuations when silent spaces of less than said unusual length occurredin the record.

One object of my invention is to produce a record and a mechanismcapable of functioning therewith wherein silent spaces of relativelyshort length may be utilized for control purposes and also to Preventnaturally occurring silent spaces from effecting unintended actuationsof said mechanism. In accordance with these objects I therefore providea sound record on which the normal sound recording has interpolatedtherewith recordings of an inaudible frequency to which the phonographpick-up is electrically sensitive or responsive. Said inaudiblefrequencies are interpolated into the sound record at all normallysilent points therein, thereby preventing the accidental occurrence of asilent space having no recorded frequency at any place in the recordexcept where such silent space is intentionally provided for the purposeof mechanism actuation or control. Consequently the normal recordproduced by my invention comprises a normal sound track with all thebreaks or silent spaces normally occurring in such sound track orsequence filled in with an inaudible frequency interpolated for thepurposes above described, said record also having silent spaces of norecorded frequency at predetermined points only where it is desired toactuate the film feed or other mechanism to be controlled. Consonantwith the foregoing it will be clear that the control and actuatingmechanism of my invention is designed to cooperate with a record of thetypedescribed; while the invention also provides means for automaticallymaking records having said characteristics.

With respect to the control and actuating mechanism provided by theinvention, said mechanism is designed and intended to operate upon anydesired length of silent or no-frequency record track. Consequently therecord as a whole is not prolonged by the interpolation of silent spacesof undue length heretofore made necessary'by mechanism intended tocooperate with such no-frequency spaces. On the other hand, my mechanismdoes not require a pick-up or operating circuit tuned to any particularfrequency, as it will operate only upon a complete absence of recorded 4frequency. Consequently the mechanism is free from the delicacy andinaccuracy of those tuned circuits which are designed to function uponor in connection with an imposed frequency of predetermined value.Furthermore, because there is no inaudible frequency superposed upon orsynchronous with the recording of normal sound, I avoid any possibilityof heterodyne currents in the pick-up. Neither is there any possibilitythat the control circuit may be unintentionally operated by the chanceoccurrence of a frequency accidentally the same as that intended for thetuned control circuit.

' The pick-up and control circuit provided by my invention is anexceedingly simple one and makes possible the construction of a devicewhich can be conveniently built into the casing of present commercialforms of combined phonograph and slide film sets.

It will be understood that the foregoing general description and thefollowing detailed description as well are exemplary and explanatory ofthe invention but are not restrictive thereof.

Referring now in detail to the present preferred embodiment of theinvention illustrated byway of example in the accompanying drawings, thegeneral layout of the apparatus is diagrammatically shown in Fig. 1. Aphonograph I is provided with uitable motor driven support for soundrecord 2 having electrical pick-up arm 3 of standard construction. Theusual pick-up circuit fl runs to a standard amplifier 5 which isconnected to a suitable loud speaker 6.

A slide film projector I is diagrammatically indicated 'as havingprojecting lens H and a conventional curved film support i2 for holdingpassing through the projector gate and, after projection, onto a curveddisposal track l3.

Conventional means for feeding said film F frame-by-frame through theprojector gate comprises sprocket wheel l which is rotatable uni,directionally to feed the engaged film by means of an actuating leverIS. The film is adapted to be advanced one frame upon rotating the levera -full stroke clockwise to the position shown in the unfed portion ofthe film roll F, the roll thence 76 Fig. 1. Ratchet wheel l8, fixed tothe wheel l5, and pawl I9, fixed to the lever l6, cause the sprocketwheel to turn with the lever during said clockwise movement of thelever, but permit the lever to have an idle return movement in thecounter-clockwise direction, said movement being effected bythe tensionspring 20. Leaf pring 2| lying against a square hub on the sprocketwheel provides for accurate register of the fed film with the gate. Thusa rearward or clockwise pull on the lever l6 causes the film to advanceone frame, while the lever returns to its original position aftercompletion of said feeding stroke so as to be in position to feed thefilm another frame on the next clockwise actuation.

Automatically controllable power means are provided by the invention foractuating the filmfeed lever i6. As embodied a motor driven gear Wheel22 is provided with an eccentric pin 23 projecting axially from its fiatsurface. A lanyard 24 is attached at one end to the lever l6 and at itsother end to the pin 23. Gear wheel 22 is mounted on a horizontal shaftwithin a casing 25. Said casing is provided with an arcuate slot 26through which the pin 23 extends. Said slot 26 is preferably ofconcentric with the travel of pin 23 and acting as stop means at eitherend of its arcuate path.

Means are provided for imparting motion to gear wheel 22, said meanscomprising electric motor 21 having gear 28 meshing with gear 22. Saidmotor is normally stationary, its line circuit 29 being normally openand under control of magnetic relay-operated switch 30 as hereinafterdescribed in detail. A helical spring 3| is mounted about the shaft ofgear wheel 22, one end of said spring being fixed to a stationary pin 32on the casing and the other inner end being fixed to a stud 33 on thewheel 22. When wheel 22 is free to turn, spring 3| causes it to rotatecounter-clockwise through the 180 are imposed by slot 26 to the positionshown in Fig. 1. By such movement the lanyard 24 will be drawn adistance sufiicient to retract lever I 6 and feed the film one frame.Upon closing the motor circuit 29, the motor will cause the gear 22 torotate in the opposite direction against the spring, return the pin 23to the opposite pointand therewith permit lever IE to return to itsinitial position whereby the film feed is ready for the next frame.

Referring'now to Fig. 2 it will be seen that the wiring diagram of thepick-up 3 and the amplifier 5 are conventional and may be of anysuitable form. As embodied, current from the Volume control 35 of thepick-up feeds into the grid of the first amplifier tube 36. The plateout-put of tube 36 is in turn resistance-coupled to the grid of secondamplifier tube 31. The plate out-put of tube 31 feeds to the out-puttransformer 38 of the loud speaker 3. A rectifier tube 39 is provided torectify the plate current of.the amplifier tubes, and preferably saidrecifier tube makes the circuit capable of use vgigh either A. C. or D.0. current from the line r nection is connected from tube 31 to tube 42by wire 43. Condensers 44 and 45 are inserted in the circuit wires 43and 45 respectively for the purpose of permitting only the A. C.component to be amplified by tube 42. A second stage of amplification inamplifier 50 is provided by tube 48 and rectification is provided by thetube 49.

As will be clear from the circuit diagram, both amplifiers 5 and 50 areenergized whenever the needle of the pick-up 3 is vibrated by somefrequency on the record If the frequency picked up by the needle iswithin the audio range, sound will be reproduced over the loud speaker6; while if the frequency is of non-audible characteristics, the circuitof amplifier 5 will also be energized but no audible sound will betransmitted from the loud speaker. In all cases, however, whenfrequency, either audible or inaudible, is transmitted to the pick-upneedle, the circuit of amplifier 50 will be energized.

The Plate signal from amplifier tube 48 energizes relay 52 forcontrolling magnetic switch 30 which is across the power line 29 of themotor 21. A condenser 65 may be inserted across the line of relay 52 toprevent chatter or introduction of any undesirable signal therein. Whenenergy is transmitted through the second amplifier 50 the relay 52 isthereby energized to hold the switch 30 open so that no current istransmitted to the motor 21. Thus whenever the pick-up encounters anyfrequency on the record the motor 2'! will be stationary. However, whena silent space of no frequency is encountered by the pick-up, the relay52 will be de-energized, thus closing switch 30 and causing motor 21 torotate. A spring 30a is provided to close switch 30 when the relay 52 istie-energized. So long as the silent, no-frequency space on the recordis in contact with the pick-up needle the energized motor will hold thewheel 22 in a position 180 opposite that shown in Figs. 1 and 2. Whenthe pick-up. needle again encounters frequency, either audible orinaudible, on the record track, relay 52 is again energized to openswitch 30 and the lanyard and lever ii are drawn back to the position ofFigs. 1 and 2 and thereby advance the film.

Thus a complete actuation of the film-feeding mechanism is effected bythe sequential effects of a silent space and a frequency or energy spaceon the record track. The silent space eifects movement of the actuationlever in one direction and the frequency effects the opposite movement.Obviously the sequence of frequency and no-frequency can be utilized inthe other order as well, merely by reversing the direction of switch 30so that the power stroke of lever may be effected when energy istransmitted to motor 21 and the return movement of the leveraccomplished by means of the frequency parts of the record. In eithercase, however, the complete cycle of actuation is effected by a sequenceof frequency and no-frequency or viceversa, on the record.

In Fig. 3 there is a diagrammatic showing of a typical record track aswould be imposed on a groove in the record in accordance with theinvention. The solid wave lines A indicate audible frequencies, whilethe dotted wave lines B indicate inaudible frequencies, which areinterpolated wherever and whenever it is desired to fill in a normallysilent space in the recording so as to prevent actuation of the filmfeed at such normally occurring silent space. For example, if theaudible frequencies A be considered as representing parts of a speech,the inaudible frequencies B would be interpolated during normal pausesin such speech as would occur for example at the end of a phrase or,sentence. Said inaudible frequencies B may be of any suitable rangeeither above or below the normal audio range. However, when it isdesired to provide actuation of the film feed by de-energizing thecircuit of amplifier 50, the record will have spaces C of no recordedfrequency and those spaces will be utilized as hereinabove described toactuate the motor switch 30 and thereby make the power stroke of thefilm-feeding lever l5. Inasmuch as the switch 30 and motor 21 will beoperated instantaneously upon the occurrence of any blank space C itwill be obvious that such spaces need not have any unusual orpredetermined length but may be of relatively short duration, forexampleone-half second, or even one-tenth second. Because of thisfeature of the invention it is possible to introduce control movementsfor the film feeding mechanism without any apparent break in thecontinuity of a sound script as for example where it may be desired tofeed the film during part of a song. For such purpose normally existingpauses of such short duration may usually be found or provided in anappropriate place in the record and such a short break in the soundwould be unnoticed, but would be suffioient to actuate the feedingmechanism.

The control mechanism of the invention is also capable of operation witha record having no interpolated inaudible frequency B. In such case(Fig. 5) the blank or no-frequency spaces C will be of a lengthsubstantially greater than any normally occurring silent space E in thespeech or music being recorded. In order to prevent undesired closingsof the switch 35 upon the occurrence of such normally silent spaces B',the condenser will be of such increased value or capacity that it willintroduce a time delay in the functioning of the relay 52. By suitablypredetermining the capacity of the condenser 50 with respect to therelatively short, normal silent spaces B in the sound sequences of therecord it is thus possible to cause the relay 52 to become de-energizedonly when a blank space C on the record exceeds the discharge capacityof condenser 50.

Referring now to the means provided by the invention for producing arecord having recorded frequencies and blank spaces of the characterindicated in Fig. 3, a suitable mechanism therefor is shown in Fig. 4.As embodied a record blank I00 is mounted in convenional manner formaking recordings thereon by a recording tool IN. The tool is providedwith suitable circuit wires I02 for receiving frequencies to beimpressed upon the record, said frequencies being converted intomechanical movement at the tool in any suitable or conventional mannernot shown.

For the transmission of sound sequences or audio frequencies to therecording tool a microphone I! is connected in conventional manner to anaudio amplifier I and thence by leads I00 to the tool circuit I02.

In accordance with the invention, oscillations of an inaudible frequencyare impressed upon the record through the tool IOI at those points B inthe sound sequence which are normally silent. For this purpose anoscillator IIO for generating inaudible frequency is connected to apower circuit at III and leads by circuit wires II2 into the toolcircuit I02. The oscillations may be of a frequency either above'orbelow the audible range for a reproducing loud speaker. I prefer to usean inaudible high frequency above 10,000 cycles per second.

Means are provided for automatically closing circuit M2 to transmit thefrequency 13 of the oscillator to the cutting tool IOI only at suchtimes as there is an absence of audio frequency from the amplifier I05,as would occur during a pause in normal speech for example. For thispurpose a relay-controlled switch I I5 is provided across the circuit II2, said switch being normally closed by a spring I I6 and adapted to beopened by energizing of a relay III. Energy is transmitted to relay II'Ithrough an amplifier I20 and said amplifier is connectedby lead wiresI2I to the out-put of audio amplifier I05. Hence whenever audio energyis being transmitted from the microphone through audio amplifier I05,the relay III will be energized and circuit II2 thereby opened. However,whenever a silence occurs in the audio sequence, switch II5 will closeand during such silence inaudible frequencies will be transmitted to thetool circuit I02 from the oscillator IIO, thereby providing thefrequency interpolations B as previously described.

For providing the blank, no-frequency spaces C on the record I00, Iprovide switching means for arbitrarily cutting out the transmission ofany frequency to the tool IOI at any desired'or predetermined point inthe record. For this purpose a double-pole switch I25 is provided acrossthe line I02 to the recording tool. Said switch I25 is manually operableby push button I26 So that the operator may interpose a blank space C atany desired point in the record by merely pushing the switch button I26for any required length of time. By so opening switch I25 it is obviousthat transmission of frequencies from both the audio amplifier I05 andthe oscillator IIO will be eliminated. For convenience of operation asignal light I21 may be connected for operation by the opening of switchI25. The second pole I28 of the switch lies across the power line I29 tothe signal lamp I2'l so that when circuit I02 is broken the lamp will belighted and vice-versa. By this means the artist or operatormaking therecord will be apprised of the timing of the blank spaces and therebyconvenienced in making the record.

The invention in its broader aspects is not limited to the specificmechanisms shown and described but departures may be made therefromwithin the scope of the accompanying claims without departing from theprinciples of the invention and without sacrificing its chiefadvantaxes.

What I claim is:

1. In a control mechanism in combination a sound record having audiblefrequencies and inaudible frequencies recorded thereon in tandemrelation, said record also having interposed blank spaces of no recordedfrequency, a pick-up, an

electrical control device operable in one'sense by transmission throughthe pick-up of either of said types of frequencies and operable in theopposite sense when the pick-up encounters one of said blank spaces.

2. In a control mechanism in combination a sound record having audiblefrequencies and inaudible frequencies recorded thereon in tandemrelation, said record also having interposed blank spaces of norecordedfrequency, a pick-up, a movable member, an electrical controlfor said member, saidcontrol being responsive to both of'said types offrequencies to move said member in one direction and responsive to saidblank spaces to move the member in the opposite direction.

3. In a control mechanism in combination a sound record havingfrequencies recorded thereon and interposed with blank spaces of norecorded frequency, a pick-up, a slide film projector having a filmcorrelated with said recorded frequencies, a film feeding means, and anelectrical control device operable in one sense when the pick-upencounters a blank space to actuate said feeding means in one directionand operable in the opposite sense when frequency is transmitted throughthe pick-up to actuate said feeding means in the opposite direction.

4. In a control mechanism in combination a slide-film projector, a filmfeeding device therefor having a two-directional movement for feedingthe film frame-by-frame, a sound record having recorded frequencies andblank spaces thereon, a pick-up for the record, and a control deviceresponsive to the effect of said frequencies on the pick-up for movingsaid feeding device in one direction and responsive to the effect ofsaid blank spaces on the pick-up for moving the feeding device in theopposite direction.

5. In a control mechanism in combination a slide-film projector, a filmfeeding device therefor, a sound record having recorded frequencies andblank spaces thereon, a pick-up for the record, a device to be actuated,a control means for said device responsive to the effect of said blankspaces on the pick-up, and means for preventing response by the controlmeans from a blank space shorter than a predetermined length.

6. The method of producing a sound record for controlling the feed of aslide film in a projector which comprises recording successive soundsequences appropriate to the successive scenes on the film to beprojected concurrently with the reproduction of the record, spacing saidsound se-' quences with blank spaces of no recorded frequency at pointsin the record corresponding to the feeding of the film from one scene tothe next, and filling all silent places in the record except thoseoccupied by said blank spaces with an inaudible recorded frequency.

'7. In a control mechanism in combination a sound record having audiblefrequencies and inaudible frequencies recorded thereon in tandemrelation, said record also having interposed blank spaces of no recordedfrequency, a pick-up, and an electrical control device operable in onesense when the pick-up encounters a blank space and operable in theopposite sense when any frequency is transmitted through the pick-up.

8. In a control mechanism in combination a slide-film projector, afilm-feeding device therefor, a sound record having recorded soundfrequencies appropriate to the successive scenes on the film to beprojected concurrently with the reproduction of the record, said soundsequences being spaced by blank spaces of no recorded irequency atpoints in the record corresponding to the feeding of the film from onescene to the next, all silent places in the record except those occupiedby said blank spaces being filled with an inaudible recorded frequency,a pick-up for the record, and control means for moving the film operablethrough the pick-up, said control means being operated to move the filmonly when the pick-up encounters one of said blank spaces and beingrestrained from film-feeding movement by either audio or inaudiblefrequencies on the record.

CONKLING CHEDISTER.

